Process of preparing same



\ Reissued May 13.

UNITED STAT ES- PATENT orrlcla;

1 rnansrnnnu'r mmarnn monoo'r AND raocnss or ranmnme SAME Oscar A. Cherry, Chicago, 1H,, and. Charles W s m D. 0., assignors'to Economy.

Fuse & Manufacturing Company, Chicago, 1112, -a corporation of New York No Drawing. driginal No. 2,207,116, dated Jul 9, 1940, Serial No. 42,885, September 30, 1935. Application for reissue October 15, 1940, Serial 4Ciaims. (elm-m a This invention relates to transparent laminated products and particularly transparent laminated tubes adapted for various industrial uses, such as electrical fuses and the like. This invention also relates to a process for producing such products.

Heretoiore, transparent tubeshave been pro duced by uniting sheetsof cellulose nitrate colloided by camphor. Similar articles have also been made from cellulose acetate, from glass, and from certain molded resins or resin-like products, as, for examplenreacondensation products, and

vinyl ester and styrol-polymerization products All of these products suffer from defects which have seriously limited their-industrial usage. The cellulose ester products and particularly the cellulose nitrate products are highly inflammable and are comparatively expensive.w Glass is, of

course, quite brittle. The urea products are less a brittle than glass but the technical difficulties in-' volved in the preparation or tubes and sheets are enormous. Furthermore, the products are not very. heat resistant and are seriously affected by moisture. The vinyl derivatives are quite lacking in heat resistance and are at present quite expensive.

The superior qualities oi the non-transparent laminated tubes now onthe market are well known. They are relatively non-inflammable, moisture resistant, strong and are nonbrittle.

Accordingly, it is an object 01' the present invention to provide a,process by which transparent, laminated'tubes may be produced.

' comprisesdrawing this invention pertains, and it is to be understood thatthe description is to be considered as illustrative and. is not to be limited except bythe scope oi the appended claims; f,

In the preparation of a tube, advantage is taken of the' fact that a cellulosic sheet will 'swell when brought into contact with certain liquids, as ior example, water, and will shrinkor contract when the swelling agent is removed. Thus, a swollen sheet is wound-into the form of a tube on a man'- drel or forming core and then dried. 'I'hecontractile forces thereby set up exert themselves in such a manner as to cause the upper layers or laminations to press tightly upon those beneath. The result is a tightly wound, laminated tube,

produced without the aid of external pressure,

and dependent upon internal forces for its rigidity and homogeneity.

The use of an adhesive in swelling agent is "desirable but not essential.

When used it may be present, for example, as asolute in the swelling agent. when gelatin-is used as the adhesive, it is preferably presentin such proportion that a l solution is formed.

A simple method of carryingout the invention a cellulose sheet through-a swelling agent, preferably water and preferably A It is another object of the present invention'to produce mechanically strong, transparent tubes.

It is a'nother objector the present'invention to provide-a process by which such products may be produced cheaply and economically.

It is another object of the present invention to produce non-inflammable, transparent, lamin'ated tubes.

Other objects will be apparent as the description of the invention proceeds.

As starting materials, a transparent cellulosic sheet is employed. As an example, the transparent cellulosic sheet known on the market as Cellophane may be employed. In conjunction with the cellulosic sheet, an adhesive therefor may be used. This adhesive may be any good. grade oigelatin or glue. In certain cases gum arable may be employed, but for reasons that will appear later the gelatine or glue is to be preferred. 1

As an illustration 01 away by which the invention may be practiced, the preparation of a transparent, laminated tube will be described; Varia tions will occur to those killed in the art to which containing adhesive in solution, and then winding the swollen sheet upon a mandrel. A 001- lapsible mandrel is preferably used since the aforementioned contractile forces are exerted in such a way as to hold the tube tightly on the mandrel, and a collapsible mandrel makes subsequent withdrawal of thwmandrel easier. The

mandrel with its windings 0t swollen sheet is,

then dried,- preferably at a. moderate temperature, as for example, approximately '15 degrees C. This method, as above described, does not permit the formation or transparent, laminated tubes possessing any great wall thickness. For

example, it has been ioundthat the wall thickness in the case of a tube having an internal diameter of one-half inch should not greatly exceed 25/1000 01' an inch. 01 course, it is desirable to produce tubes of greater thicknesses. i It has been found. as a result of experimen tation that it the. thin walled .tube produced as above described is, after drying andwhile still on the mandrel, supplied with an additional wrapping of an'equal or less thicknessand again; dried that the wrappings tightly adhere, and that,

thereby a transparent tube wltha wall thickness of twice that above described is obtained. process may be repeated and thus transparent conjunction with the tubes of any desired wall thickness may be ob-- tained.

In order to obtain non-inflammability in the product, flame-proofing materials may be dissolved in the swelling water. A 6 to 10 per cent solution of a mixture of 80 percent ammonium bromide and 20 per cent di-ammonium hydrogen phosphate gives excellent results. In this case, gum arabic may not be used as the adhesive employed since the salts will precipitate it from solution. 1

'If desired, the laminated products may be material into a tube having a'. plurality of supersuperficially waterprooied by being coated with a waterproofing varnish or lacquer. This varnish should preferably be substantially colorless and transparent.

In all cases, the ceilulosic materialis expanded or swollen prior :to' its app ication to the mandrel "or forming core and therea'fter'dried to allow the laminated material thus formed to contract; and I adhere in the manner above described.

Articles so produced are rigid and strq .3 due to the contraction of the overlying laminations which sets up internal stresses which are resisted by the stress in the outwarddirection of-the underlying laminations which-were dried and.

hardened on the mandrel or core.

The ,teriri'fcellulosic material" as used in the specification andclaims is. intended to include only thosecellulosic materials which are cap- .able of being softened and swelled in liquids which are not solvents for' the ceilulosic material employed. Furthermore, this-term does not inelude Ciellophane of the-type available on the market whichhas been treated with moistureproof materials, such as would. prevent the Cellophane from being swelled in liquids which are not solvents for the Cellophane.

. ,What is claimed is: j 1. The method of producing a transparent tube, which comprises placing an elongated, thin,

transparent sheet of cellulose material capable of softening and swelling in water in contact with wateruntil the-same has become softened and swollen, thereupon applying said sheet while in a soft and swollen condition to a mandrel in superimposed laminations tightly applied one upon the other to form a tube of such limited thickness asto preserve the transparency of the tube, and thendrying the tube so formed and thereafter applying additional layers of watersoftened and-swollen transparent cellulose matesoftened and swollen condition one upon the rial by tightly winding a sheet of the same on said previously formed and dried tube and again limiting the thickness thereof to preserve the transparency of the tube, and drying the additional laminations so applied.

2. The method of producing a transparent tube, which comprises winding a transparent lying laminations thereof.

of-each application before drying bing insuf- 'tube, which comprises contacting atransparent sheet into a tube having a plurality of superto materially impair the transparency of the vlose material softened and swollen 'as'aforesaid, said additional layers being insuflicient in when subsequently dried, and from drying the as having its laminations tightly adhered and as sheet of water-softened and swollen cellulose imposed laminations, but insumcient in number to materially impair the transparency of the V tube when subsequently dried, drying the tube, thereafter winding and dryingon said tube another sheet of transparent. cellulose material softened and swollen as aforesaid, and repeating said winding and drying operations with a sheet of said treated material until a tube of desired thickness is produced, the number of laminations the-resulting tube when dried. 3. The. method of producing a transparent ficient to materially impair the transparency of sheet of cellulose material capable of softening and swelling in water, with water containing an adhesive until the cellulose material has become softened and vswollen, thereupon winding said imposed laminations but in'suflicient in number tube when subsequently dried, drying the tube, thereafter applying additional layers by winding on said tube another sheet oftransparent cellunumber to materially impair the transparency of the resulting tube, and then drying the additional layers. I 4. A transparent article ofcommerce in the form of a -tube or the like, comprising a substantially homogeneous shrunken mass of predetermined thickness composed of a plurality ofspirally wound sheets of transparent cellulose material, each=sheet being wound uponitself to form a plurality .of successively applied lamlnaa tions, said sheets being in that form which re sults from winding them successively in a water other to an extent producing a plurality of. superimposed laminations insufficient in number to' impair the transparency of the tube so'formed initially formed tube and thereafter winding thereon another sheet of transparent ceilulosic material in a softened and swollen condition as aforesaid, and repeating'said operation until the final tube of desired thickness is produced; said transparent article being further characterized possessing rigidifying and strengthening stressesproduced by contractile forces and forces resisting said contractile forces exerted by the under- Osman/CHER Y.

{CHARLES A. CABELL. 

